Shivam Hospital Logo

How Thyroid Disorders Affect Fertility and Pregnancy Outcomes

Picture of the author

The thyroid gland, an essential organ in the body, it's important in regulating metabolism, energy production, and hormonal balance. For women in their reproductive years, thyroid function is especially significant because it directly impacts fertility and pregnancy outcomes. Both hypothyroidism (underactive thyroid and hyperthyroidism (overactive thyroid) can lead to complications during conception, pregnancy, and postpartum recovery. Among these, hyperthyroidism requires careful attention due to its complex effects on maternal and fetal health.

Hyperthyroidism Before Pregnancy

Hyperthyroidism occurs when the thyroid gland produces an excessive amount of triiodothyronine (T3) and thyroxine (T4), which can lead to symptoms such as rapid heartbeat, weight loss, anxiety, tremors, and irregular menstrual cycles. For women trying to conceive, these symptoms can interfere with ovulation, making it harder to become pregnant.

Undiagnosed or uncontrolled hyperthyroidism can also increase the risk of miscarriage, infertility, and complications in early pregnancy. Hence, women with known thyroid conditions or symptoms of hyperthyroidism in women should undergo thyroid function tests before attempting to conceive. Early diagnosis and management significantly improve the chances of a healthy pregnancy.

How Does Hyperthyroidism Affect Pregnancy?

Pregnancy naturally influences thyroid hormone levels due to hormonal changes and increased metabolic demands. However, in women with hyperthyroidism, these changes can intensify the condition, leading to serious complications for both the mother and the baby.

Uncontrolled hyperthyroidism during pregnancy can cause some common risks:

  • Miscarriage
  • Preterm birth
  • Preeclampsia (high blood pressure in pregnancy)
  • Placental abruption
  • Intrauterine growth restriction (IUGR)
  • Low birth weight
  • Heart failure or thyroid storm (a rare, life-threatening escalation of symptoms)

These complications highlight the importance of managing thyroid hormone levels throughout pregnancy with the help of a specialist.

Management of Hyperthyroidism During Pregnancy

The primary goal in managing hyperthyroidism during pregnancy is to keep thyroid hormone levels within a safe range for both the mother and the fetus. Management typically involves:

  • Antithyroid medications:
    • Propylthiouracil (PTU) is usually prescribed for the first few days of pregnancy.
    • Methimazole may be recommended in the second and third trimesters due to lower liver toxicity risk.
  • Frequent monitoring: Thyroid levels are checked every 4–6 weeks to adjust medication dosages as needed.
  • Multidisciplinary care: Regular consultations with an endocrinologist and obstetrician ensure comprehensive care.

The thyroid gland of the developing baby can be negatively affected by radioactive iodine treatment during pregnancy, so it will be avoided.

Side Effects of Thyroid Medication During Pregnancy

While antithyroid medications are essential, they can carry some risks. PTU, although safer in early pregnancy, may cause liver problems in rare cases. Methimazole, if used in the first trimester, has been linked to rare congenital anomalies, which is why its use is delayed until later trimesters when possible.

However, the risk of birth defects or liver issues is significantly lower than the risks posed by untreated hyperthyroidism. Physicians always aim to prescribe the lowest effective dose of medicine for hyperthyroidism to reduce potential side effects. Stopping medication without consulting a healthcare professional can pose significant risks.

Risks After the Baby is Born

Close monitoring is necessary for mothers with hyperthyroidism and their newborns after delivery. Babies born to mothers with untreated or poorly managed hyperthyroidism may face risks such as:

  • Maternal antibodies passing through the placenta cause neonatal hyperthyroidism.
  • Low birth weight
  • Irritability and feeding problems
  • Developmental delays occur if thyroid dysfunction continues unchecked.

Newborns typically have temporary symptoms that can be managed with proper medical attention through appropriate hyperthyroidism treatment. Breastfeeding is generally safe while on antithyroid medications, as only small amounts pass into breast milk.

For personalized guidance and care, consult the doctor at Shivam Women and Children Hospital. Expert teams are dedicated to supporting women through every pregnancy and hormonal health stage.

Call Video Consultation Book Appointment